For many years it has been desired to make plastic materials from polymers such as polyvinyl chloride (PVC) and polyvinyl acetate (PVAc), which are either biodegradable by microorganisms or environmentally degradable such as in a landfill. In spite of considerable efforts, landfills are becoming inundated with plastic materials, and articles made therefrom, that will not degrade perhaps for centuries. This is especially true for vinyl halide polymer materials such as PVC that are considered non-biodegradable, that is, they persist in landfills under anaerobic conditions indefinitely without noticeable decomposition. This factor limits the acceptance of PVC in many products where its useful balance of properties and low cost would be attractive. An example is that of printable film and sheet. If a sample of flexible (plasticized) PVC is tested per ASTM D 5526, Standard Test Method for Determining Anaerobic Biodegradation of Plastic Materials Under Accelerated Landfill Conditions, there is no appreciable weight loss or change in appearance after 100 days at 97° F. in contact with simulated household waste. In contrast, cellulosic polymers and other biodegradable plastics, such as polylactic acid and polycaprolactone, are completely consumed.
There has been a particular need for a compostable polymer composition for use in many end products such as polyvinyl chloride or polyvinyl acetate films, banners, billboards, signs, laminates, ink jet media, diapers, hygienic pads and the like. These products must satisfy properties for practical purposes such as tear strength, tensile and impact strengths to function in many useful articles. However, the same properties that make them useful lead to their lack of biodegradability. PVC, PVAc and other vinyl polymers have achieved widespread usage. However, the explosive growth of such thermoplastics has aggravated the problem of disposing of them, and has caused their accumulation in landfills. Very little of these polymeric waste products degrade in most landfills because of anaerobic conditions. The problem has become aggravated because of the shortage of landfills and municipalities are seeking to restrict the use of plastics because of their inability to degrade in landfills.